Kind of sounds shady the way you are asking this question. They have every right to validate your shadowing hours if they feel enabled to do so. Also, if you do somehow get an interview with a school then they will probably ask you about your shadowing experience and how it impacted your decision to choose medicine, furthermore it is very easy to tell if someone is lying about shadowing..believe me. Most DO schools require a letter from a physician and some even require the letter to be strictly from a DO. Once you start filling out your AACOMAS you will realize how to log the information correctly. If you are unsure, then AACOMAS has a FAQs sections that will answer any question you may have. If you don't find your answer, then you can e-mail or call them for the information you are seeking out. As far as hours go...there are no SET amount of hours needed or that are ideal for a favorable candidate. What is important is, did you learn anything? Did it help you progress further into your ultimate decision? Can you see yourself doing this for the rest of your life? Also, shadowing is good because becoming a physician is a life long commitment, shadowing gives the student some kind of perspective and opportunity to ask questions of the physician to see if that is really what YOU want to do.